The present disclosure relates to a power supply unit.
A power supply unit, such as a voltage supply unit for powering a consuming device with electrical energy, frequently has a protective element, such as a melting fuse or a line circuit breaker with electromagnetic triggering. The protective element may be designed to interrupt an electrically conducting connection between the power supply unit and the consuming device when an electrical current flowing through the protective element exceeds a predetermined threshold value. For example, in the event of a short circuit in the consuming device, the electrical current will rise. By interrupting the electrically conducting connection, an overloading of the power supply unit and overheating of the connecting lines between the power supply unit and the consuming device can be avoid.
The high electrical current needed for a brief period for interrupting the electrically conducting connection between the power supply unit and the consuming device is often provided at least partially by a capacitance, e.g. a capacitor, disposed in parallel with an output of the power supply unit. Frequently, the capacitance discharges in the event of a short circuit in the consuming device, with a discharge current which is difficult to control. This can result in overheating of connecting lines between the power supply unit and the consuming device. Further, another consuming device connected in series to the consuming device in question can be damaged. It is further noted that the duration during which the discharge current of the capacitance may flow is determined by the dimensioning of the capacitance, the resistance of the connecting lines, and the short-circuit resistance of the consuming device.